Animal classification is about sorting animals into their different categories. Knowing the different categories, even if it's just the names, will help the children recognise and sort these animals. Discuss what categories the different woodland animals you've looked at may be sorted into.
The different animal categories are: mammals, reptiles, fish, amphibians, birds and invertebrates
Start by looking at the different groups, from the PDF and then have a go at the worksheet. You could also pretend to be different animals from the groups, after you call out the group name, or you pretend to be an animal and your child tells you what group you belong to.